471771292-17-THERMAL-POWER-PLANT-ppt-1.pptx

power plant instrumentation

1. NALANDA COLLEGE OF ENGINEERING, CHANDI (NALANDA) BIHAR- Submitted By:- Prof. KULDEEP DWIVEDI Dept. EEE THERMAL POWER PLANT

2. Contents:- Introduction Block diagram Main & auxiliary equipment's Explanations of equipment’s Site selection Recent development of power generation Advantages Dis advantages Contribution of Different power plants in power generation.

3. Introduction:- A thermal power station basically work on the Rankine cycle. In India 65% of total power is generated by the Thermal Power Stations . In thermal generating stations coal, oil, natural gas etc. are employed as primary sources of energy . Coal is burnt in a boiler which converts water into steam. The expansion of steam in turbine produces mechanical power which drives the alternator coupled to the turbine.

4. Block Diagram:-

5. Diagram of a typical coal- fired therm al power station :-

6. Main and auxiliary equipments :- Coal handling plant Pulverizing plant Draft fans Boiler Ash handling plant Turbine Alternator Condenser Cooling towers and ponds Feed water heater Economizer Super heater and Reheater Air preheater

7. Coal Handling Plant:- The function of coal handling plant is automatic feeding of coal to the boiler furnace. A thermal power plant burns enormous amounts of coal. A 200MW plant may require around 2000 tons of coal daily following are the process of plant-: Unloading process Feeding process Screening process Crushing process Stacking process Reclaiming process Bunkering process

8. Pulverizing Plant :- In modern thermal power plant , coal is pulverized. ground to dust like size and carried to the furnace in a stream of hot air. Pulverizing is a means of exposing a large surface area to the action of oxygen and consequently helping combustion. Pulverizing mills are further classified as: Contact mill Ball mill Impact mill

9. Draft System :- The circulation of air is caused by a difference in pressure, known as Draft. Draft is a differential pressure b/w atmosphere and inside the boiler. It is necessary to cause the flow of gases through boiler setting It may be Natural draft Mechanical draft

10. Boiler:- A boiler is a closed vessel in which water under pressure, is converted into steam. It is one of the major components of a thermal power plant always designed to absorb maximum amount of heat released in the process of combustion. Boilers are of two types- Fire tube boiler Water tube boiler

11. Ash Handling Plant :- The percentage of ash in coal varies from 5% in good quality coal to about 40% in poor quality coal Power plants generally use poor quality of coal . thus amount of ash produced by it is pretty large . A modern 2000MW plant produces about 5000 tons of ash daily. The stations use some conveyor arrangement to carry ash to dump sites directly or for carrying and loading it to trucks and wagons which transport it to the site of disposal

12. Steam Turbine :- A steam turbine converts heat energy of steam into mechanical energy and drives the generator. It uses the principle that steam when issuing from a small opening attains a high velocity. This velocity attained during expansion depends on the initial and final heat content of the steam. This difference b/w initial and final heat content represents the heat energy converted into kinetic energy. These are of two types :- Impulse turbine Reaction turbine

13. Alternator :- Turbine and alternator are mechanical coupled with each other. Alternator convert mechanical energy of turbine into electrical energy. The electrical output from the alternator is delivered to the bus bar through transformer.

14. Condenser : Steam after rotating steam turbine comes to Condenser refers here to the shell and tube heat exchanger installed at the outlet of every steam turbine in Thermal power stations of utility companies generally. These condensers are heat exchangers which convert steam from its gaseous to its liquid state, also known as phase transition. In so doing, the latent heat of steam is given out inside the condenser. Where water is in short supply an air cooled condenser s often used. An air cooled condenser is however significantly more expensive and cannot achieve as low a steam turbine backpressure (and therefore less efficient) as a surface condenser. The purpose is to condense the outlet (or exhaust) steam from steam turbine to obtain maximum efficiency and also to get the condensed steam in the form of pure water, otherwise known as condensate, back to steam generator or (boiler) as boiler feed water

15. Cooling Towers And Ponds :- A condenser needs huge quantity of water to condense the steam . Most plants use a closed cooling system where warm water coming from condenser is cooled and reused Small plants use spray ponds and medium and large plants use cooling towers . Cooling tower is a steel or concrete hyperbolic structure having a reservoir at the base For storage of cooled water Height of the cooling tower may be 150 m or so and diameter at the base is 150 m

16. Feed Water Heater :- Advantages of heating water before feeding back to the boiler:- Feed water heating improves overall plant efficiency. The dissolved oxygen and carbon dioxide which would otherwise cause boiler corrosion are removed in feed water heater Thermal quantity of steam produced by the boiler is increased. Some other impurities carried by the steam and condensate, due to corrosion of boiler and condenser are precipitated outside the boiler .

17. Economizer :- Flue gases coming out of the boiler carry lot of heat. An economizer extracts a part of this heat from flue gases and uses it for heating feed water. This use of economizer results in saving coal consumption and higher boiler efficiency

18. Super heater :- Super heater is a component of a steam- generating unit in which steam, after it has left the boiler drum, is heated above its saturation temperature. The super heater may consist of one or more stages of tube banks arranged to effectively transfer heat from the products of combustion. Super heaters are classified as convection , radiant or combination of these.

19. Reheater :- Some of the heat of superheated steam is used to rotate the turbine where it loses some of its energy. Reheater is also steam boiler component in which heat is added to this intermediate-pressure steam, which has given up some of its energy in expansion through the high-pressure turbine. The steam after reheating is used to rotate the second steam turbine where the heat is converted to mechanical energy. This mechanical energy is used to run the alternator, which is coupled to turbine , there by generating electrical energy.

20. Air Preheater :- An air pre heater increases the temperature of air supplied for coal burning And it driven from the flue gases. Air is drown from the atmosphere by the force of draft fan. Air preheaters may be of three types Plate type Tubular type Regenerative type

21. SITE SELECTION :- Transportation network. Power transmission network. Geology and soil type : oil and rock layer that can withstand the weight and vibration of power plant. Topography : It is proved that high elevation has a negative effect on production efficiency of gas turbines. In addition , changing of a sloping area into a flat site for the construction of the power plant needs extra budget. Earthquake and geological faults : Even weak and small earthquakes can damage many parts of power plant intensively. Water resources : Enough water supply . Environmental resources : Far enough from national parks , wildlife , protected areas , etc. Population centres : Enough distance from population centres . Climate : Parameters such as temperature, humidity , wind direction and speed affect the productivity of a power plant.

22. Recent developments of power generation

23. The fuel used is quite cheap. Less initial cost as compared to other generating plants. It can be installed at any place irrespective of the existence of coal. The coal can be easily transported to the site It require less space as compared to Hydro power plants. Cost of generation is less than that of diesel power plants . Advantages :

24. Disadvantages :- It pollutes the atmosphere due to production of large amount of smoke and fumes. It is costlier in running cost as compared to Hydro electric plants. Maintenance cost is more

25. Contribution of different power plants in power generation